This invention relates to an improved method of making mattresses.
A standard mattress comprises a core contained within an attractive fabric envelope. Most commonly, the core includes an inner spring assembly comprising an array of coil springs, covered top and bottom by pads of felt or other material. Alternatively, the core may be made of foam, or closed chambers containing water or air. Whatever the core construction, it is covered by an envelope made of top and bottom pieces of textile fabric whose edges are interconnected by sewing to a fabric border strip that runs around the periphery of the mattress. The seams may be protected by a decorative fabric tape.
Mattresses may, in addition, have a “pillow top” attached to the top of the mattress (and to the bottom also, if the mattress is to be reversible). While the pillow top contains its own padding, distinct from that of the core mattress, it is not separable, and in fact is sewn to the mattress. The pillow top appears to be separate, however, because corners are formed at the top of the mattress border, and at the bottom of the pillow top border, so that a neck is formed in the material. In profile, there is a V-shaped indentation at the mattress-pillow top interface. Although sewn together, the pillow top and the core mattress components are—and appear to be—distinct, being made from separate pieces of cloth and padding. The construction of pillow-top mattresses is complex, and involves a good deal of hand work, plus seam closure steps which require an operator to guide a mobile sewing machine around the periphery of the partially assembled mattress.
A pillow top mattress having, for example, an inner spring core is currently made by the following steps (where the steps numbers match the figures which illustrate them).                1a. A pillow top border 10 strip, folded lengthwise, is attached to a strong, inelastic polyester non-woven sheet 12, slightly larger than the inner spring 14, by stitching 16 at an offset distance of about two inches inward from the periphery of the sheet. The person doing the sewing lays out vee-shaped miter notches 18 where the corners are to be, and sews the edges of the miters together to form corner seams 20, during this step.        1b. A strip of strong non-woven material (“flange”) 22 is then attached to the product of step (1a), by two parallel lines of stitching, one (24) at the edge of the sheet, and one (26) between the edge and the stitches applied in step (1a).        1c. Insulation 28 is applied to the top and bottom of a core 14. Now the product 32 of step (1b) is placed over the core and insulation, and is secured to the core by clips applied at intervals of several inches. The assembly is inverted, and a second product 32 is applied in a similar manner (if the mattress is to have pillow tops on both sides; for a non-reversible mattress, the bottom border may be simply seamed to a bottom sheet or quilted panel).        1d. Now a core border strip 40 is placed around the inner spring, and the core border strip is connected to the flange 22 by machine sewing which adds a tape 42 over the seam simultaneously.        1e. Padding 44 is then adhered to both the top and bottom of the mattress, and a pillow top 46 panel is placed over the padding. The panel is sewn to the top edge of the border strip by a hand-guided track-mounted sewing machine (not shown) which adds a tape 48 to the seam as it unites the materials.        
Similar methods are used to produce mattresses not having inner springs, in which case the core border is attached to the core by appropriate alternative methods, such as by adhesion or by anchors attached to the core.
In our U.S. Pat. No. 6,874,215, we disclosed a method for making mitered corners on pillow top mattresses, in which the mattress border strip and the pillow top border strip(s) were separate items, joined by sewing after notches had been cut out of their edges to help form mitered corners. The notches had to be kept in alignment as the sewing was done. We now disclose below a method of forming the mattress border strip and the pillow top border strips as one piece, thus avoiding the need to sew the pieces together, and the need to maintain alignment between the notches. The method described in U.S. Pat. No. 6,874,215 is illustrated in FIGS. 2a-2e. 